Onset target escapes the background perceptual grouping

Abstract

Visual attention and perceptual grouping both save us from being overloaded by the vast amount of inputs: the former accomplishes by selecting specific information for further processing, and the latter by organizing a complex visual scene into reduced clusters of similar properties. It is long assumed that both attentional selection and perceptual grouping require consciousness, but this view has been challenged in recent years by empirical findings suggesting the opposite. In this study, we study whether awareness of a collinear contour is a prerequisite of its interplay with selective attention. We employed a phenomenon that attentional search was delayed when a target overlapped spatially with a collinearly grouped distractor in comparison to when a target did not overlap with the distractor (Jingling and Tseng, 2013). We first identified that visible long (= 9 elements), but not short (= 3 elements) collinear distractor slowed observers' detection of an overlapping target. Then we masked part of a long distractor (= 9 elements) with continuous flashing color patches (= 6 elements) so that the combined dichoptic percept to observers' awareness was a short collinear distractor (= 3 elements). We assessed whether the invisible parts impacted selective attention the same way as supra-threshold collinear parts. We found that the invisible collinear parts, like visible ones, could join the visible parts to form a full-length contour to impair search. This implies that collinear integration does not require awareness of all elements, and the interaction between collinear grouping and attention is likely at an early site where awareness is not critical for processing